ExpiringMap

ExpiringMap is used when we want to store self-expiring objects.

Example

First we initialize object holder

var map = new ExpiringMap();

Then we put two objects in it:

map.put("foo",{someNumber:321});
map.put("bar",{someString:"test string"});

and if within next 60 seconds we try to get key foo: map.get("foo");

//returns {someNumber:321}

if we wait longer than 60 seconds (default expire time)

map.get("foo");

//returns false

You can also specify default object timeout on init: var map = new ExpiringMap({defaultTimeout:20}); //in seconds

Or you can specify timeout for each key individually: map.put("foo",{someNumber:321}, 600); //expire key foo after 600 seconds

On Expire Callbacks

Also you can define callback for each key

map.put("foo",{someNumber:321}, 30, function(key, data){
    console.log("key "+key+" has expired, data was:");
    console.log(data);    
});

Callback will be executed when we call get method for this key again after expiration time map.get("foo");

//this will trigger callback on key foo

Or when we call getKeyList after expiration time map.getKeyList();

//this will trigger callbacks on all expired keys

ExpiringMap Methods

Method summary
boolean	put(key, object, timeout)
Object/boolean	get(key)
boolean	remove(key)
Array	getKeyList()
Object	getKeyInfo(key)
Number	getAccessed(key)
Object/boolean	getWithMetadata(key)

getWithMetadata

put(key, object, timeout, callback)

• key - name under this object will be stored
• object - object to store
• timeout - [optional] expiration timeout (in seconds), if not provided default timeout will be used
• callback - [optional] on expire callback function returns true on successful input or false if key already exists

get(key)

• key - name under object is stored

returns stored object or false if key doesn't exists

remove(key)

• key - key to be removed

returns true if successfully removed or false if object has already expired or it didn't existed in the map

getKeyList()

returns array of currently active keys, or empty array if there is no active keys left

getInfo(key)

• key - name of object

returns object with information about stored object

for expired object it will return: { expired: true, info: null }

for active object if will return: { expired: false, info: { createdTimestamp: 1299118422871, endTime: 1299118482871, modifiedTimestamp: 1299118422871, timeout: 60 } }

where:

• createdTimestamp - timestamp when this key is created
• endTime - timestamp after which object under this key will expire
• modifiedTimestamp - last accessed timestamp
• timeout - key timeout in seconds

getAccessed(key)

• key - name under object is stored

returns last accessed timestamp for this key

getWithMetadata(key)

• key - name under object is stored

returns stored object along with meta data